132 PESTS OF GARDEN AND FIELD CROPS 
grains here and there in a green, growing field. Often the stem below 
the head will be somewhat shriveled or discolored. A tiny maggot may 
be found within the stem. The adult is a small fly with a striped body. 
The first generation of 
flies emerge in early sum- 
mer from the young plants. 
Their offspring are the brood 
of maggots that cause the 
blanched heads. 
The adults of these mag- 
gots emerge after normal 
threshing time, and there 
follows a midsummer gen- 
eration on volunteer grain 
or wild grasses. Adults 
from these lay eggs on fall 
wheat or native grasses, and 
the maggots from these sur- 
vive the winter, completing 
growth in the spring. On 
fall wheat they injure the 
base of the plant. 
Prompt threshing and 
stacking will kill many of 
the insects in the ripe straw, 
and bury the survivors in 
Fic. 113. — The Wheat-stem Maggot. Adult, : : i u 
enlarged, and work, natural size. Original. the stack where the flies can- 
not get out to go through 
the midsummer generation on grasses. Late sowing of fall wheat 
probably will help to some extent. 
The Stalk Borer (Papaipema nitela Guen.) 
The stalks of many kinds of plants, such as tomato, corn, oats, 
barley, and others, are attacked by a worm which bores into them 
from without, feeds within, and frequently bores out again, moving 
